The present invention relates to a process for manufacturing a glass substrate coated with at least one layer of ink(s) (organic or inorganic ink(s)) forming one or more designs, for example one or more monochromic or polychromic coloured designs, this (these) design(s) being made of one or more inks suitable for coating glass, preferably of one or more light-fast inks for example made of an enamel or of several enamels.
In the prior art, the manufacture of sheets of glass bearing light-fast multicolour decorations or images is carried out by applying to the sheet of glass, by hand or by serigraphy, the desired multicolour images, consisting of ceramic or enamel inks for firing, followed by firing the images or decorations.
During the use of serigraphy, several serigraphy operations must be carried out one after the other depending on the number of colours (each colour requiring a serigraphy passage), it being understood that each printing operation must be followed by a drying operation before printing the next layer of ink. This printing is viable only when the same image or the same decoration must be applied to a large number of sheets of glass. For printing a small number of items with the same image or the same decoration, multicolour serigraphy is very expensive since a separate screen is required for each base colour. In addition, the cost of making an cleaning the serigraphy screen is very high.
For small runs, or when individual images, designs or decorations are concerned, enamels or ceramic inks can also be applied by hand to the sheet of glass. The application by hand of inks for firing onto the surface of the glass is, however, associated with specific requirements in terms of inks and dexterity of the person performing this operation, the inks applied remaining for a long time in a state in which they can easily be blurred during the process for applying the various colours one after the other, on account of the lack of absorption capacity of the surface of the glass and the specific properties of the inks for firing which are usually used.
The aim of the invention is to provide a process for manufacturing (a) glass substrate(s) bearing (a) design(s) based on ink(s), in particular on light-fast ink (s), this process being suitable for manufacturing, at low cost and without any risk of deterioration of the colours, small series of glass substrates bearing (a) coloured design(s), this process also making it possible to obtain varied designs with good graphic quality in a rapid and reproducible manner.
This aim is achieved by the process according to the invention, in which a model of the desired design(s), consisting of ink(s) or coloured material(s) of any type and being on one or more supports of any type, are taken, the desired design(s) on the model is (are) converted into digital or analog data (or a signal), the data (or signal) obtained is processed using image-processing software and the desired design(s) is (are) reproduced (or reconstituted), in the form of one or more layers of ink(s), on the glass substrate with the aid of a printing means connected to the computer carrying the image-processing software. In other words, the desired design s) is (are) reproduced on the glass substrate from a model by means of a reproduction device comprising a device for capturing (or taking) images, image-processing software and a printing means. The design(s) is (are) then generally fired at suitable temperatures (i.e., for example, at high temperature for inorganic inks such as enamels, in particular to temperatures of about 450 to about 750xc2x0 C.).
The process according to the invention makes it possible to print any type of design on any type of glass surface without needing to change the reproduction device as a function of the design to be printed (unlike the serigraphy process in which each design requires a specific serigraphy screen). Moreover, in the case where one (or more) coloured design(s) is (are) produced and in which a colour printing means (such as a device with printing head(s) or decoration head(s) or a plotter) is used, it is possible to carry out the printing in a single passage, irrespective of the number of colours, thereby allowing a gain in production efficiency as well as suppression of the drying operations between the operations for applying the different colours. In addition, depending on the choice of model, the process in accordance with the invention makes it possible to distinguish and to determine the desired colours and shades on a model more quickly than on the glass substrate on which it is generally necessary to carry out a firing operation before obtaining the final colours. The process in accordance with the invention also makes it possible to reproduce already-existing images, decorations or designs directly, i.e. to transfer them directly onto the glass substrate, and the printed design (s) obtained has (have) very good graphic quality (it is possible in particular to reproduce photos in a satisfactory manner).
It may be noted, when an enamel-type light-fast ink for firing is used, that the printed design(s) has (have) excellent durability after firing, the fired enamels showing good attachment to the glass, good hardness and good colour-fastness.